Maintenance of Luteal Function in the Cow

A series of experiments conducted over a period of several years has provided the following evidence that LH plays a major role in stimuIating corpus luteum growth and progesterone synthesis in cattle:Purified bovine LH and other LHcontaining preparations overcome the inhibitory effects of concurrently injected oxytocin on luteal tissue weight, progesterone content, and concentration; whereas, other pituitary hormones, including prolaetin, FSH, and growth hormone are incapable of overcoming the inhibitory effects of oxytocin.Single injections of purified bovine LH in Freund's adjuvant given at mid-cycle significantly prolong the functional life span of the corpus luteum and lengthen the estrous cycle.LH-containing preparations and crude bovine anterior pituitary extracts significantly increase corpus luteum weights and progesterone contents in hysterectomized heifers.The administration of equine antibovine LH serum causes partial regression of corpora lutea in hysterectomized heifers.Incubation of LH-containing preparations with urea abolishes their luteotropic properties.Progesterone synthesis in vitro by bovine luteal tissue slices is stimulated by purified bovine LH.The reaction is highly sensitive, specific, and is inhibited by addition of equine anti-bovine LH serum.